You might notice in the log files of a client or on the Notification Server itself, an error regarding "Class Not Registered -2147221164" error. This seems to occur possibly when basic inventory is being run or sent, along with other situations that the agent handles.
It could be possible that the .dll files associated with the agent did not register completely during an install or upgrade.
This should easily be solved by running the /registerclient switch using the AeXAgentUtil.exe program located under the \altiris\altiris agent directory. This can be scripted to a remote computer that is experiencing this behavior or run right from the Start > Run area.